I don't find any process to synthetize piperonal from 3-4 dihydroxybenzaldehyde. Is it possible to do like the first step of this synth with benzaldehyde insteed benzene?

[url=https://www.thevespiary.org/rhodium/Rhodium/chemistry/safrole.html

---

... crazy synth for sweet dreams ...

3,4-dihydroxybenzaldehyde is also known as protocatechualdehyde.
Methylenation reactions can be found in

https://www.thevespiary.org/rhodium/Rhodium/chemistry/methylenation.html#methylenation

Post 225611

(foxy2: "Re: 4-Methylaminorex Synth w/o CNBr", Novel Discourse)

Post 225616

(foxy2: "Re: 4-Methylaminorex Synth w/o CNBr", Novel Discourse)

Keep reading.

---

Do Your Part To Win The War

Thanks !
But now the problem is that I don't own an autoclave. Is it possible to replace CH2Cl2 by CH2BR2(b.p. 97°)and reflux the whole instead heat under presure?

---

... crazy synth for sweet dreams ...

Yes, dibromomethane or diiodomethane may be used instead. In the link I posted there are a PTC reaction which does not use an autoclave too.